stems cells

                 What are Stem Cells?                        

       Stem cells are cells found in most multi-cellular organisms. they are cells that have the ability to grow and become many different cell types in the body during early life and growth. Stems cells are characterized by the potential to renew themselves through mitotic cell division. they  also serve as an internal repair system in many tissues. They divide, basically with no limits to replace other cells while the person or animal is alive. When a stem cell divides, each new cell has the ability, to stay a stem cell or to become another type of cell with a more specific function, such as a muscle cell, a red blood cell, or a brain cell.



        How Were Stem Cells Discovered?                        

         James E. Till and Ernest A. McCulloch, both Canadian scientist, contributed findings in the research of stem cells. They were the fist to discover the adult stem cells. They started their research by injecting bone marrow cells into irradiated mice, they discovered visible lumps that were observed in the spleens of the mice, that were proportion to the number of bone morrow that was injected to the mice. Till and McCulloch called the lumps “spleen colonies” and assumed that each lump arose from a single marrow cells which was possibly a stem cell.


     What are Challenges When Researching Stem Cells?   


    There are many challenges in the research of stem cells. For example, scientists would like to be capable to grow a specific type of cell in the laboratory and then insert it into a patient, where it would replace diseased tissue. However, stem cells are not being used yet to treat disease because scientists still haven't learned how to direct a stem cell to differentiate into a particular tissue or cell type and to control that differentiation once the cells are inserted into a person. For example to treat diabetics, scientists need to not only create insulin-producing cells, but they need to be capable of regulating how those cells produce insulin once they are in the body.

 Another challenge that scientist are facing in the research of stem cells include the need for some sort of signal to actually trigger the stem cells to differentiate. Like in nature stem cells are triggered to differentiate by internal and external cues. The internal cues are genes inside each cell, which are like a series of instructions that dictate how is should function. The external cues are chemicals released by other cells or interactions with other cells, which may change the way the stem cell functions. Due to the fact that turning genes on and off is a crucial to the process of differentiation, scientist have been experimenting by inserting certain genes into culture dishes and then using those genes to try and extract stem cells to differentiate specific types of cells. However the challenging part of this, is the fact that some sort of signal is needed to trigger the stem cell to differentiate. Therefore, Scientists are still searching for this signal.

   Rejection is also a challenge of stem cell research. When a patient is injected with stem cells taken from a donated embryo, his or her immune system may see the cells as foreign invader and launch an attack against them. Moreover, using adult stem cells can overcome this obstacle, because stem cells taken from the patient would not be rejected by his or her immune system. However adult stem cells are not as flexible than embryonic stem cells and are more difficult to manipulate in the lab.


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